package com.hmdp.utils;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

@Component
public class RedisIdWorker {
    /**
     * 开始的时间戳
     */
    private static final long BEGIN_TIMESTAMP = 1640995200L;
    /**
     * 序列号的位数
     */
    private static final int COUNT_BITS = 32;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    public RedisIdWorker(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public long nextId(String keyPrefix){
        //1.生成时间戳
        LocalDateTime now = LocalDateTime.now();
        long nowSecond = now.toEpochSecond(ZoneOffset.UTC);
        long timestamp = nowSecond - BEGIN_TIMESTAMP;
        //2.生成序列号
        //2.1.获取当天日期，精确到天
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        //2.2.自增长
        long count = stringRedisTemplate.opsForValue().increment("icr:" + keyPrefix + ":" + date);
        //不用包装类便于运算，报黄但实际不出现空指针
        //3.拼接并返回
        return timestamp << COUNT_BITS | count;
        // <<左移运算符，将时间戳左移32位，低位全是0，用或运算将序列号填充
    }
//    public static void main(String[] args){
//        LocalDateTime time = LocalDateTime.of(2022, 1, 1, 0, 0, 0);
//        long second = time.toEpochSecond(ZoneOffset.UTC);
//        System.out.println("second ="+second);
//
//    }
}
